Tried that - it didn't work.
However I managed to sort this issue late last night. Downloaded and installed Slingplayer (was using the desktop version earlier), and whilst it had issues with the finder ID I was able to create the Internet connection on the slingplayer web site using an explicit IP address.
I just bought a Slingbox Pro HD. It's working fine, I can watch TV via SlingPlayer. However when I attempt to assign it to my account I get a popup message advising that the application cannot find the Finder ID - so the Slingbox can't be defined against my account.
After much fiddling around I was eventually able to locate the Slingbox ID. However when I attempt to define that ID on my account I am advised that the ID is not valid. And yet I scraped and pasted the ID from the Slingbox software.
I have manually configured my router to port forward port 5001. The Slingbox is visible on my LAN. But I can't persuade the Slingbox web site to recognise my Slingbox.
I'm getting really p'd off about this. I'm deaf so I can't phone Slingbox UK for support - and there don't appear to be any options for me to open a support case via email.
This Slingbox is going back to the supplier for a refund if I can't get this issue resolved.